============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz.4.739/6804 is trying to acquire lock: ffffc900063570d8 (&rb->spinlock){-.-.}-{2:2}, at: __bpf_ringbuf_reserve+0x1d5/0x5c0 kernel/bpf/ringbuf.c:415 but task is already holding lock: ffffc90006b7d0d8 (&rb->spinlock){-.-.}-{2:2}, at: __bpf_ringbuf_reserve+0x1d5/0x5c0 kernel/bpf/ringbuf.c:415 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&rb->spinlock); lock(&rb->spinlock); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by syz.4.739/6804: #0: ffffffff8db2daa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #0: ffffffff8db2daa0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #0: ffffffff8db2daa0 (rcu_read_lock){....}-{1:2}, at: bpf_test_timer_enter+0x1a/0x140 net/bpf/test_run.c:36 #1: ffffc90006b7d0d8 (&rb->spinlock){-.-.}-{2:2}, at: __bpf_ringbuf_reserve+0x1d5/0x5c0 kernel/bpf/ringbuf.c:415 #2: ffffffff8db2daa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #2: ffffffff8db2daa0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #2: ffffffff8db2daa0 (rcu_read_lock){....}-{1:2}, at: trace_call_bpf+0xbf/0x6b0 kernel/trace/bpf_trace.c:134 stack backtrace: CPU: 0 PID: 6804 Comm: syz.4.739 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/06/2026 Call Trace: dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106 check_deadlock kernel/locking/lockdep.c:3090 [inline] validate_chain kernel/locking/lockdep.c:3884 [inline] __lock_acquire+0x690e/0x7ea0 kernel/locking/lockdep.c:5171 lock_acquire+0x1bc/0x4a0 kernel/locking/lockdep.c:5790 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xb0/0x100 kernel/locking/spinlock.c:162 __bpf_ringbuf_reserve+0x1d5/0x5c0 kernel/bpf/ringbuf.c:415 ____bpf_ringbuf_reserve kernel/bpf/ringbuf.c:466 [inline] bpf_ringbuf_reserve+0x58/0x70 kernel/bpf/ringbuf.c:458 bpf_prog_1a4bcee3237edce2+0x2d/0x4a bpf_dispatcher_nop_func include/linux/bpf.h:1016 [inline] __bpf_prog_run include/linux/filter.h:608 [inline] bpf_prog_run include/linux/filter.h:615 [inline] bpf_prog_run_array include/linux/bpf.h:1698 [inline] trace_call_bpf+0x322/0x6b0 kernel/trace/bpf_trace.c:135 perf_trace_run_bpf_submit+0x79/0x1c0 kernel/events/core.c:10018 perf_trace_lock+0x301/0x390 include/trace/events/lock.h:50 trace_lock_release include/trace/events/lock.h:69 [inline] lock_release+0x8ad/0x920 kernel/locking/lockdep.c:5801 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:149 [inline] _raw_spin_unlock_irqrestore+0x6d/0x120 kernel/locking/spinlock.c:194 __bpf_ringbuf_reserve+0x478/0x5c0 kernel/bpf/ringbuf.c:453 ____bpf_ringbuf_reserve kernel/bpf/ringbuf.c:466 [inline] bpf_ringbuf_reserve+0x58/0x70 kernel/bpf/ringbuf.c:458 bpf_prog_0ad8d11286bf4265+0x36/0x90 bpf_dispatcher_nop_func include/linux/bpf.h:1016 [inline] __bpf_prog_run include/linux/filter.h:608 [inline] bpf_prog_run include/linux/filter.h:615 [inline] bpf_prog_run_pin_on_cpu include/linux/filter.h:632 [inline] bpf_flow_dissect+0x130/0x410 net/core/flow_dissector.c:922 bpf_prog_test_run_flow_dissector+0x431/0x640 net/bpf/test_run.c:1552 bpf_prog_test_run+0x31c/0x390 kernel/bpf/syscall.c:3748 __sys_bpf+0x62b/0x780 kernel/bpf/syscall.c:5112 __do_sys_bpf kernel/bpf/syscall.c:5198 [inline] __se_sys_bpf kernel/bpf/syscall.c:5196 [inline] __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:5196 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f2f7cba94d9 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f2f7da0f028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 00007f2f7ce26360 RCX: 00007f2f7cba94d9 RDX: 000000000000004c RSI: 0000200000001100 RDI: 000000000000000a RBP: 00007f2f7cc3804e R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f2f7ce263f8 R14: 00007f2f7ce26360 R15: 00007ffd1cd28a48